When you position your hand horizontally, grab one's face and proceed to swiping in a downward motion, palm down; Usually done when one is acting in a foolish manner. Can be done with wet hands for better results.

As a group of friends rock out to a 80's hair band genere of music, Mo sings the wrong refrain to a commonly known song and as a result to this Tom hits her up with a solid "facewash"